Diagnosing champion generator.

[38racing]

I was given a champion 4000 with 196 cc. Fellow had been using at the racetrack but has sat for awhile. He felt the generator was shorting and loading engine to stall. He said that he checked the carb. I'm just getting started. I can start it right up and I can keep it running on about 1/2 choke but rpm is low and it vibrates like heck. That's with circuit breaker off. Turning breaker on makes no difference but a lamp will light dimly. I'm thinking I'll check valve clearance and try the carb I took off my King generator to convert to propane and ng. I would think if end bearing of rotor was seized then it wouldn't pull start so normal.

[RoyM]

If the stator was shorted it would be very hard to turn over due to the strong magnetic field and it is producing power. Check the valve lash, .004"-.006" Intake .005"-.007" Exhaust should be close enough. What did he mean by "checking the carb"? If you suspect the generator end remove the brushes to eliminate any issues there.

[38racing]

If the stator was shorted it would be very hard to turn over due to the strong magnetic field and it is producing power. Check the valve lash, .004"-.006" Intake .005"-.007" Exhaust should be close enough. What did he mean by "checking the carb"? If you suspect the generator end remove the brushes to eliminate any issues there.

I assume he meant that he checked it out including cleanliness. He's my auto mechanic and runs dirt modified racecars.

[Arkie]

What is the engine model, type, etc?
Model of complete gen also would be a help?

Also DO NOT WALK OFF away from the gen and leave it running out of site just yet.
I've seen them small gens start genning smoke and heavy flames, sometimes after running for 20-30 mins due to the gen section overheating, especially if the motor gets up to speed and no electric being generated. Can burn down the neighborhood.'

Also do not assume the good mechanic checked out the small engine good.

I seen a Stihl chainsaw in a really good auto mechanics trash pile and asked him if I could have it for parts.
He said sure, I bought a new Stihl because that one has low compression.
Long story short, it did not have low compression, did not need any parts, and was a minor repair for me and is my favorite go to chainsaw. (some auto mechanics just hate small engines)

[38racing]

it's a c46535 with 196 cc.
I checked valves . some specs I found indicate .006 and .008 and I was 5 and 8 so I don't think valves are the issue. I did a leakdown and I was 50% with good air flow out the muffler but that valve has the compression release. I was putting in 40 psi and holding crank with a breaker bar. If I rotated the crank clockwise my hissing went away and leakdown was almost 0 so I expect It was piston misplacement at the 50%.

[Arkie]

Did you swap out the carb as you mentioned previously?????

I've seen the insides of them 6.5HP champion engines carbs turn to severe rust.

[38racing]

Did you swap out the carb as you mentioned previously?????

I've seen the insides of them 6.5HP champion engines carbs turn to severe rust.

Just got the replacement carb mounted. Off on some other projects today.

[38racing]

Exact same performance with replacement carb. Only runs with partial choke. Tach says 1500 rpm and not a smooth 1500. Would late timing from sheared flywheel key be a possibly? No kick back issues when starting.

[RoyM]

You either have too much air or not enough fuel, timing has nothing to do with choke operation.

[KE4AVB]

Hmmm. Without the actual model number it is hard to look up any info on this generator.

Being a gasoline powered it will be most likely a two pole alternator that must run at 3600 rpm (60 hz, USA)under load and run at 3750 off load; unless, it has an idle down feature. They simply not normally designed to idle. Even if it has an idle down feature 1500 seem too slow. Now if this unit is being on a 50 hz electrical then it must operated under load at 3000 rpm.

Besides the operating frequency is very important for most electric motors and critical for some electronics.

The only generators the operate under load at 1500-1800 rpm are diesel power unit with 4 pole alternators.